Frequently Asked Questions About Sentinel-1 Data
Level-1 products can be one of two product types — either Single Look Complex (SLC) or Ground Range Detected (GRD). Level-2 Ocean (OCN) products can have different components available depending on the acquisition mode. Products are designated based on their acquisition mode, product type and, in the case of Level-1 GRD, resolution. All products are processed directly from the Level-0 product. Each mode can potentially generate Level-1 SLC, Level-1 GRD and Level-2 Ocean products. For WV mode, the Level-0 and Level-1 products are not distributed. Level-2 OWS component is not available from the TOPSAR modes.
The naming convention is explained in the graphic at right (click for a larger image). For more data information, see the Sentinel-1 Data and Imagery page.
You must be logged in to Vertex in order to download Sentinel-1 data from ASF. If you don't already have a user account at ASF, please click here to create one.
To filter by data product, use the drop-down menu titled <Add to Queue by type...> at the bottom of the results column. Use the menu to select only those products you want added to your download queue. The <Find> bar, at the top of the results column, lets you filter your results by typing in keywords displayed in the granule description, such as path or flight direction.
For more detailed sorting, use the <Add to Queue by type...> and <Find> features, and add the results to your download queue. Click the <Download Metadata (.csv)> button, and import the resulting file into a spreadsheet. Use the tools in your spreadsheet to sort the metadata — for example, by polarization. Copy and paste the resulting granule names into the <Granule List> window to the left of the map and click <Search>.
Find additional Vertex help through the <Help> tab at the top left of the page.
Use the geographic search option in the Vertex Data Portal to identify your area of interest and download Sentinel-1 products available from ASF DAAC.
A Sentinel-1 product refers to a directory folder that contains a collection of information. It includes:
- a 'manifest.safe' file which holds the general product information in XML
- subfolders for measurement datasets containing image data in various binary formats
- a preview folder containing 'quicklooks' in PNG format, Google Earth overlays in KML format and HTML preview files
- an annotation folder containing the product metadata in XML as well as calibration data
- a support folder containing the XML schemes describing the product XML.
The default Windows file extraction utility will often fail because of long Sentinel-1 filenames. The open-source utility 7-Zip can be used to extract the .zip files downloaded from ASF and ESA.
These beam modes incorporate an acquisition technique (TOPSAR) that produces wide swaths from multiple sub-swaths, or bands, acquired in the direction the satellite is moving. This can create "seams" that are more noticeable in cross-polarized images (HV and VH). IW is acquired using three sub-swaths and EW five sub-swaths. See Image Quality for examples.
The S1A browse (below right) is a geocoded jpeg image displayed in a polar stereo map projection at latitudes above 65 degrees north and south. The Vertex map (below left) always displays a granule in a Mercator projection. The browse image below is also an example of stepping (question #10). See Image Quality for more information on image artifacts and anomalies.
Note: OCN (Wave mode) products never have browse or thumbnail images available.